Methane is a primary constituent of landfill gas (LFG) and a potent contributor to greenhouse gasses. MSWFs are the largest source of human-related (anthropogenic) methane emissions in the United States, accounting for about 25 percent of these emissions in 2004. Additionally, these escaping LFG emissions are a lost opportunity to capture and use a significant energy resource. Substantial energy, economic, and environmental benefits are achieved by capturing LFG prior to release, which subsequently reduces greenhouse gasses. LFG capture projects improve energy independence, produce cost savings, create jobs, and help local economies. LFG is currently extracted from landfills using a series of wells and a vacuum system that consolidates the collected gas for processing. From there, the LFG is used for a variety of purposes including motor vehicle fuel, generator fuel, biodiesel production, natural gas supplement, as well as green power and heating.
Currently, MSWFs bury waste in layers over time (See FIG. 1A). The basic structure is a floor and sidewalls of compacted clay, covered with a HDPE polymer liner, filled with layers of waste alternated with clay or soil layers. Once a landfill has reached a certain capacity, methane recovery wells are installed and gas is extracted from decay and composition of waste layers. As the waste body increases in height, non-apertured “riser pipe”, “casing”, “riser”, or “vertical pipe” is added to the existing extraction well (See FIG. 1B). These terms may be used interchangeably for the tubular members extending into the waste body. Once the waste body reaches the design height or capacity it is covered with compacted soil, topsoil, or possible liner material and subsequently replanted with natural vegetation and left to decompose. LFG is created as the organic fraction of solid waste decomposes in a landfill, due to the process of methogenesis. LFG gas consists of about 50 percent methane (CH4), the primary component of natural gas, about 40-49% percent carbon dioxide (CO2), and a small amount of non-methane organic compounds. Landfills must be monitored over time to ensure that LFG emissions, groundwater leachate, and waste from the solid waste unit are not being released and impacting the environment. Methane extraction and recovery captures LFG and prevents emission of these air contaminants. Methane is first produced in the older, lower decomposing waste bodies. Subsequent layers produce methane at different times and rates (See FIG. 1C). Currently, to extract methane from subsequent layers, wells are drilled to a desired depth or elevation and methane extracted. As decomposition continues shallower and shallower wells are required to reach gasses trapped in upper waste bodies. Currently, to extract LFG from upper shallow zones, a MSWF must drill new, shallower wells, which is a capital intensive process. Multiple wells, pipe, equipment and repeated drilling are required to collect and transport the gas to the collection facility. LFG extraction, recovery and use is a reliable and renewable fuel option that represents a largely untapped and environmentally friendly energy source at thousands of landfills in the U.S. and abroad.
Capture of LFG can be used to produce electricity with engines, turbines, microturbines, or other technologies, used as an alternative to fossil fuels, or refined and injected into the natural gas pipeline. Capturing and using LFG in these ways can yield substantial energy, economic, environmental, air quality, and public health benefits. Internationally, significant opportunities exist for expanding LFG recovery and use while reducing harmful emissions.
Problems exist to rehabilitate existing non-functional wells, for example the wells are often on side slopes or on uneven ground making access difficult. In addition, the pipes often bend and deviate after installation and deviate during waste placement. Annular obstructions from couplers or lag screws or similar type fasteners used to connect additional pipes or risers add to the difficulty of rehabilitation efforts. The position of the landfill gas well, typically protruding from the surface makes a conventional drilling method, i.e., a drilling rig, problematic and renders this methodology difficult, when used to rehabilitate or fix a non-functional well. Many methane well locations are logistically difficult and impossible to reposition and reenter an existing well with conventional equipment. Trying to insert drill pipes in the annulus of methane gas wells is difficult due to deviations and bends in the well casing. These and other issues severely limit the reliable available methods which can be used to achieve success in the well rehabilitation and production enhancement process. A tool and method of ventilating existing methane wells is required that would not damage the vertical pipe while allowing methane gas to enter the riser from waste bodies and various elevations within the same well location and would operate safely in this type of environment.